radionuclide transport will enhance radionuclide migration in fractured chalk for those radionuclides with exceedingly high affinity for colloids.Remobilization of radiocesium from anoxic sediments can be an important mechanism responsible for long-term contaminations of lakes. However, it is unclear whether such remobilization occurs in shallow lakes, where concentrations of dissolved oxygen in the hypolimnion (bottom DO) change temporally in response to meteorological conditions, and whether remobilized radiocesium influences the activity in fish. We examined the seasonal dynamics of the activities of dissolved 137Cs and 137Cs in fish (pond smelt and crucian carp) from Lake Kasumigaura, a shallow, hypereutrophic lake, five years after the Fukushima Daiichi Nuclear Power Plant accident. The activities of both dissolved 137Cs and 137Cs in fish declined during that time, but the declines showed a clear seasonal pattern that included a summer peak of 137Cs activity. The activity of dissolved 137Cs increased when the bottom DO concentration decreased, and a nonlinear causality test revealed significant causal forcing of dissolved 137Cs activity by bottom DO. The fact that NH4-N concentrations in bottom waters were higher in the summer suggested that remobilization of 137Cs from sediments could result from highly selective ion-exchange with NH4-N. Despite the shallow depth of Lake Kasumigaura, winds had little influence bottom DO concentrations or dissolved 137Cs activities. The fact that seasonal means of 137Cs activities in pond smelt and crucian carp were positively correlated with the seasonal means of dissolved 137Cs activities suggested that remobilized 137Cs may have influenced the seasonal dynamics of radiocesium in fish through food-chain transfer, but higher feeding rates in warm water could may have also contributed to the seasonal dynamics of 137Cs activity in fish. Our findings suggest that in shallow lakes, intermittent but repeated hypoxic events may enhance remobilization of radiocesium from sediments, and remobilized radiocesium may contributed to long-term retention of radiocesium in aquatic organisms.In recent years, nanoscale zero-valent iron (nZVI) has been gradually applied in soil remediation due to its strong reducing ability and large specific surface area. Compared to conventional remediation solutions, in situ remediation using nZVI offers some unique advantages. In this review, respective merits and demerits of each approach to nZVI synthesis are summarized in detail, particularly the most commonly used aqueous-phase reduction method featuring surface modification. In order to overcome undesired oxidation and agglomeration of fresh nZVI due to its high reactivity, modifications of nZVI have been developed such as doping with transition metals, stabilization using macromolecules or surfactants, and sulfidation. Mechanisms underlying efficient removal of organic pollutants enabled by the modified nZVI lie in alleviative oxidation and agglomeration of nZVI and enhanced electron utilization efficiency. In addition to chemical modification, other assisting methods for further improving nZVI mobility and reactivity, such as electrokinetics and microbial technologies, are evaluated. The effects of different remediation technologies and soil physicochemical properties on remediation performance of nZVI are also summarized. Overall, this review offers an up-to-date comprehensive understanding of nZVI-driven soil remediation from scientific and practical perspectives.Magnetic biochar has been widely used in the removal of aquatic pollutants due to its strong adsorption capacity and recyclability. However, the nutrient deficiency caused by magnetic biochar reduces plant performance and limits its use. The effects of magnetic biochar (derived from either eucalyptus wood or pig manure compost) on soil Cd, Zn, and Pb bioavailability to Phragmites australis L. (reed) and soil microbial community were investigated in a pot experiment. We also examined treatments of magnetic biochar with P supplementation and unmodified biochar with Fe addition to elucidate the mechanism by which magnetic biochar affects plant growth. We found that the addition of magnetic biochar significantly reduced the concentrations of available heavy metals in soil and inhibited heavy metal uptake by reeds. It also promoted the formation of iron plaque on reed roots to inhibit metal translocation. However, compared to unmodified biochar, magnetic biochar reduced reed performance, as indicated by the reduced plant biomass and photosynthetic ability, and it also reduced the biomass of soil bacteria and fungi. This was due to the interception of P by the iron plaque and the reduced concentration of soil available P. https://www.selleckchem.com/products/dx600.html Collectively, although magnetic biochar exhibited a strong potential for heavy metal remediation, P supplementation is recommended to maintain plant performance and soil health when applying magnetic biochar.Synthetic pesticides such as neonicotinoids are commonly used to treat crops in tropical regions, where data on environmental and human contamination are patchy and make it difficult to assess to what extent pesticides may harm human health, especially in less developed countries. To assess the degree of environmental and human contamination with neonicotinoids we collected soil, water and people's hair in three agricultural regions of the Philippines and analysed them by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS-MS). Five neonicotinoids, namely acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam were targeted. Residues of neonicotinoids were found in 78% of 67 soil samples from the three provinces. Total neonicotinoid loads ranged on average between 0.017 and 0.89 μg/kg in soils of rice, banana and vegetable crops, and were 130 times higher (113.5 μg/kg) in soils of a citrus grove. Imidacloprid was the most prevalent compound at an average of 0.56 μg/kg in soil while thiacloprid was below the limit of detection. Half of the eight water samples from a rice field and nearby creek contained residues of imidacloprid (mean 1.29 ng/L) and one contained thiamethoxam (0.15 ng/L). Residues of neonicotinoids were found in 81% of 99 samples of people's hair from the surveyed regions (average total concentrations 0.14 to 1.18 ng/g, maximum 350 ng/g). Hair residue levels correlated well with the concentrations of thiamethoxam and total residues in soils from the same locality (r = 0.98). The presence of thiacloprid in 15% of the hair samples but not in soil samples suggests an additional route of exposure among people, which is most likely to be through ingestion of agricultural food and drinks available in the market.